Filters are useful for water treatment and purification. Water and wastewater filters typically include sand, gravel, anthracite, activated carbon (e.g., granular activated carbon (GAC)), or other filter media. For example, granular media filters typically comprise particulate filter beds comprising sand, anthracite, etc. The filter bed is typically supported by a floor in the filter assembly configured to divide the filter assembly into an inlet side and an outlet side.
During use and operation of the filter assembly, a fluid stream may pass through the filter media. As the fluid passes through the filter media, suspended solids and other particulate matter may be removed and retained by the filter media, purifying the fluid stream. Purified fluids (i.e., filtrate) passing through the filter assembly may be collected by an assembly (e.g., a collection assembly) which may include, for example, a manifold including laterals and a header conduit (which may also be referred to as an “underdrain assembly”). In some embodiments, the collection assembly may include a perforated false bottom to support the filter media bed and to provide a system of fluid passageways for collecting the filtered fluid from the bottom of the filter assembly.
After a predetermined volume of fluid has passed through the filter media or a predetermined amount of solids have been retained by the filter media, the filter media may be considered “saturated” (i.e., “loaded”) with the suspended solids. The filter media may be regenerated to remove the suspended solids from the filter media by a process referred to in the art as “backwashing.” Backwashing includes passing a backwashing fluid (e.g., water, air, or both) upward through the collection assembly to the filter bed to remove the suspended solids from the filter and form a backwash fluid highly concentrated with the suspended solids. Because the collection assembly may also operate to distribute a fluid to the filter bed, the collection assembly may also be referred to herein as a distribution assembly. The distribution assembly may operate to substantially uniformly distribute the backwashing fluid (e.g., liquid or gas) through the filter bed.
Fabrication of distribution and collection assemblies for a filter system or other system typically requires welding the distribution assembly to the system. Components of the distribution assembly may be threadably attached to each other, welded to each other, or both to form the distribution assembly. However, threaded attachments and welded connections are difficult to form and often suffer from weak connections that are unable to withstand significant pressure drops to which the distribution assembly may be exposed.